This invention relates to a novel oxepane isomer of 42-O-(2-hydroxy)ethyl-rapamycin, a process for its preparation, and its use in treating, preventing or inhibiting transplant rejection, graft vs. host disease, autoimmune diseases, inflammatory diseases, adult T cell leukemia/lymphoma, solid tumors, fungal infections, and hyperproliferative vascular disorders, among others.
The structure and synthesis of 40-O-(2-hydroxy)ethyl rapamycin, also known as SDZ-RAD or RAD-666, is described in U.S. Pat. No. 5,665,772 (Cottens, et al.) and International Patent Publication No. WO 94/09010. When prepared according to U.S. Pat. No. 5,665,772, SDZ-RAD exists as a mixture containing about 95 wt % of Isomer B and 30 wt % of Isomer C (the oxepane isomer).
40-O-(2-hydroxy)ethyl rapamycin is now known as 42-O-(2-hydroxy)ethyl rapamycin, due to a change in numbering convention. SDZ-RAD is an analog of rapamycin, which is a macrocyclic triene antibiotic produced naturally by Streptomyces hygroscopicus. 
Rapamycin has been found useful in an array of applications based on its antitumoral and immunosuppressive effects. Uses include preventing or treating systemic lupus erythematosis, pulmonary inflammation, insulin dependent diabetes mellitus, smooth muscle cell proliferation and intimal thickening following vascular surgery, adult T-cell leukemia/lymphoma, and ocular inflammation. Rapamycin and rapamycin derivatives, including SDZ-RAD, continue to be studied for treatment of these and other conditions.